"He is the master." At the premiere of "War Horse," praise like this for the movie's director wasn't hard to come by.

For Tom Hiddleston, working with a director as talented as Steven Spielberg meant more than just acting under a guy who has made dozens of timeless films. Hiddleston told MTV News on the red carpet premiere of "War Horse" that working with Spielberg was more like a crash course in classic movie magic.

Spielberg recently directed the "Thor" star in "War Horse," a World War I-era drama about the connection between a boy and his horse. Hiddleston shared a few of the lessons he learned from the legendary director.

"He's a master craftsman," he said. "And what I learned from him, really, is that he's so impeccably prepared."

Hiddleston recalled Spielberg's habit of storyboarding many of the film's scenes, but that never stopped the director from making changes on the fly and running with them. "He turns up on set every day with an open mind and an open heart, because he still doesn't know where the magic is. And every day, there is magic that will happen."

But for Spielberg to find that magic, he has to keep both this cast and crew on their toes. For Hiddleston, this often meant changing direction on a moment's notice. "He just has to be sharp enough and on point enough that he's there to catch it and to keep his crew nimble and fleet of foot," Hiddleston explained. "So that if he suddenly sees something like the sun's in a particular place or something's happening between two actors, or in this case, an actor and a horse, that he can capture that, the beauty of the accident, and it lasts forever on film."